Garden Talk: October 13, 2005

From NGA Editors

Five Steps to Bulb Planting Success

The best time to plant spring bulbs depends on where you live. Ideally, wait until the soil temperature is below 60°F. As a general guide, plant in September through early October if you live in USDA Hardiness Zones 4 or 5; October to early November in zones 6 or 7; and November to early December in zones 8 and 9. Plant bulbs that have been refrigerated for 8 to 10 weeks in late December to early January in zone 10.

To discourage voles or gophers, add a handful of sharp gravel to the planting hole or plant bulbs in wire or fabric baskets. Don't mulch where rodents are a problem.

Layer two different species, such as tulips and grape hyacinths, in the same bed for exciting color combinations. Plant tulips first, then add enough soil to achieve the proper depth for the grape hyacinths. Plant the grape hyacinths between the tulips.

Set the bulbs in a planting bed or in separate planting holes with their roots or basal plate downward. If you are unsure which part of the bulb is the bottom, plant the bulb on its side.

Plant a variety of bulbs to extend the flowering season. In addition to daffodils and tulips, include some early-flowering bulbs, such as crocuses, snowdrops, and scilla, to herald the start of spring. Late-flowering alliums will continue the show into early summer.

Fall Cleanup Q and A

Cutting Back PerennialsQuestion: After the first frost, should I cut back the flower stalks on my perennials? Or is it best to leave them as is and cut them back in the spring?
Answer: If winter temperatures in your region are regularly below 0 degrees F, don't cut back the perennials until late winter or early spring. The dead foliage helps protect the plants from cold. After the ground freezes, cover the whole bed with a loose layer of straw. Leave it until early spring and then gradually remove it as temperatures warm.

Pruning Ornamental Grasses Question: What is the proper method of cutting back ornamental grasses for the winter?
Answer: Most gardeners wait until after the grasses have bloomed so that they can enjoy the ornamental plumes. The seedheads are also attractive in winter, so you may want to wait until spring to trim them. Then, cut the dead grasses back to about 6 inches; the new growth will quickly cover the old stubs. Some gardeners use a hedge trimmer, as this is much faster than using a hand clipper.

Composting LeavesQuestion: I would like to make a 4x4x4 fenced-in area and compost fall leaves. If I fill the bin in early November, will the leaves decay by the middle of May, when I can rototill them into the soil?

Answer: Composting essentially stops when the weather turns cold, and plain fallen leaves alone can take a year or more to decompose. To speed up the process, shred the leaves with your lawn mower, then till them into the soil this fall. By spring they should be decayed enough for planting.

Shrub Dogwood Trials

Shrub forms of dogwood (Cornus) make excellent landscape plants and are widely used by landscapers around the country. They are known for their green or variegated foliage, attractive flowers and fruits, fall foliage color, and colorful stems in winter. However, with so many dogwood varieties available, it's often difficult for homeowners to choose the best one.

Since 1999 Longwood Gardens in Kennett Square, Pennsylvania, has been evaluating 33 different types of shrub dogwoods for plant habit, size, foliage, flowering, fruiting, and pest resistance at their USDA zone 6 public garden. They have rated each species on a scale of 1 to 5 for each characteristic. Here are the top-scoring dogwoods by category.

The top-ranked species dogwood was Cornus sericea var. coloradensis. This North American native had better leaf, stem, and fruiting than other species and a more symmetrical, round habit.

The top variegated-leaf dogwood was Cornus alba 'Argenteomarginata'. This cultivar has beautiful green and white variegated leaves with a tinge of rose coloring in summer. It was especially resistant to disease.

The best yellow-twigged dogwood was Cornus alba 'Bud's Yellow'. It has exceptional stem color from a distance. The best red-stemmed dogwood was Cornus sericea 'Baileyi'. It stood out for its bright stems and nice plant form.

New Variegated Hedge Plant

If youre looking for a tough shrub to plant this fall that provides beauty, versatility, and low maintenance, consider the variegated beauty briar (Eleutherococcus sieboldianus variegatus). This fast-growing, deciduous shrub reaches 6 to 8 feet tall and wide at maturity. It has attractive green and white, fan-shaped leaves, and white flowers in spring. The calling card of the beauty briar, though, is its toughness. Beauty briar will grow in heavy shade or full sun; it tolerates poor soil, air pollution, and heavy pruning; and it has few pest and disease problems.

Plus, if youre trying to create a barrier hedge to keep people and animals out of a garden, beauty briar sports small, sharp thorns on its branches. Beauty briar is hardy in USDA zones 4 to 8.